Flat bottom bag



w E. SHRUM 3,485,439

FLATBCTTOM BAG Filed Dec. 4, 1967 2 Sheets-Shee,t 1

' INVENTOR. AMY/1am (fish/um ETTORNEY W. E. SHRUM FLAT BOTTOM BAG Dec.23, 1969 2 Sheets-Sheet- Filed Dec. 4, 1967 INVENTOR. lv/Y/l'am E. ShrumH 77' ORNE Y US. Cl. 229-58 8 Claims ABSTRACT OF THE DISCLOSURE Thisinvention pertains to a flat bottom bag formed from flexible tubularmaterial by making a pair of folds and a single seal. Specifically, thebag is formed by longitudinally folding the edge portions of a collapsedflexible tube inwardly to a superposed position on the main body portionthereof not extending beyond the longitudinal center line of the tube. Atransverse seam is then formed across the width of the tube adjacent thefree edges at one of its ends securing together therealong the overlyingplies comprising the folded tube. This completes the structure of abasic bag element from which a flat bottom bag can be formed. Severalmethods are taught as suit-able for shaping the secured end of the abovebag element to form the desired flat bottom structure. For example, byturning the bag element inside out and shaking out its folded edgeportions a flat bottom bag is readily obtained.

DESCRIPTION OF THE INVENTION To increase the fill capacity in bagconstruction it has become customary to utilize a square or fiat bottombag structure. To this end a considerable number of bag designs havebeen proposed in the past. One of the most popular of these comprisesforming inverse folds or gussets at the opposite edge portions of atubular body and then securely closing one of the two ends of the tube,i.e., by forming a transverse seam across the width of the tube adjacentthe end to be closed. While this method often produces a satisfactorybag, fabrication can be difficult since customarily the tube must befirst inflated in order for forming members to press inwardly and formthe gussets. The inflating of the bag in a continuous operation whereina continuous length of tube is employed is not entirely a simple matter.Here it is not uncommon to provide complicated and specially designedapparatus to maintain the tube in an inflated condition during theperiod the gussets or inverse folds are being formed along its side oredge portions.

Accordingly, it is an object of the present invention to provide animproved method for forming flat bottom bags wherein only a couple foldsneed be made and a single seal effected to form a bag element from whicha square or flat bottom bag can be easily obtained.

Another object of the present invention is to provide a method forforming a fiat or square bottom bag from continuous flexible tubularmaterial wherein only a minimum of equipment is required and wherein thetube can be maintained in a collapsed condition during the forming ofthe bag.

Another object of the present invention is to provide a bag element orarticle inexpensively and easily fabricated and from which a squarebottom bag can be readily obtained by a single shaping step.

Yet another object of the present invention is to provide an improvedsquare bottom bag wherein the raw or free edges adjacent the seam at theclosed end of the bag are hidden within the confines thereof to providea flat bottom bag easily fabricated and esthetically appealing forparticular uses, as, for example, pouches in United States Patent O MPatented Dec. 23, 1969 which expensive articles can be more readilymerchandized.

Briefly then, this invention contemplates an improved method for forminga flat bottom bag from tubular material wherein a minimum of equipmentis required. Basically, only a couple of folds and a. single seam needbe made to provide a basic bag element from which a square or flatbottom bag can be readily obtained. Specifically, the closed edgeportions of a flexible tube are longitudinally folded inwardly,respectively, to a superposed position on the main body portion of thetube short of its longitudinal center line. A transverse seam is theneffected across the width of the folded tube at one end thereof securingtogether therealong the overlying plies comprising the folded tube, andthereby completing the construction of the basic "bag element desired.The seamed end of the bag element can then be shaped by one of severaldifferent methods to provide a flat bottom bag. In one method, the bagelement is turned inside out and the flat bottom is shaken out. Here thefree or raw edges adjacent the transverse seam are placed within theconfines of the bag such that its general or overall appearance isenhanced. By again turning the above obtained bag inside out, a bag witha somewhat differently formed flat bottom structure is provided. Anothermethod of suitably shaping the bag element to provide a flat bottomincludes the strategic separation of the walls of the bag element nearits seamed end.

Other objects and advantages of the present invention and its details ofconstruction will be apparent from a consideration of the followingspecification and accompanying drawings wherein:

FIGURE 1 is a schematic isometric view showing a method of forming, in acontinuous. operation, a bag element embodying the principles of thepresent invention;

FIGURE 2 is an enlarged cross-sectional view taken along reference line2-2 of FIGURE 1;

FIGURE 3 is an enlarged fragmentary view of a portion of the bag elementof FIGURE 1;

FIGURE 4 is an enlarged isometric fragmentary view of the bag element ofFIGURE 1 showing a method of shaping the seamed end thereof to provide aflat bottom;

FIGURE 5 is a view like FIGURE 4 onl showing a portion of the flatbottom as shaped;

FIGURE 6 is an isometric View of a bag including a flat bottom portionshaped by the method portrayed in FIGURES 3 and 4;

FIGURE 7 is an enlarged cross-sectional view taken along reference line77 of FIGURE 6;

FIGURE 8 is an isometric view of a bag including a flat bottom portionshaped by turning the bag element of FIGURE 1 inside out and shaking outits folded edge portions; and

FIGURE 9 is an enlarged cross-sectional view taken along refernce line9--9 of FIGURE 8.

Referring particularly to FIGURE 1, there is shown a bag element 10formed from a continuous tube 12 of heat scalable material. Bag element10, when properly shaped, is useful to provide a square or flat bottombag as is explained more fully hereinafter.

Tube 12, in a generally collapsed, non-inflated condition, is fed fromroll stock 14 under and edgewise upwardly about folding mandrel 16 tonip rollers 18 and 20. Folding mandrel 16 assisted "by nip rollers 18and 20 longitudinally or laterally folds the edge portions 22 and 24 oftube 12 to a position upon the main body portion 26 thereof definedbetween the longitudinal fold lines 23 and 30. The folded tube 12, withfour overlying plies at its folded edge portions 22 and 24, and twooverlying plies at locations therebetween like that shown in FIG- URE 2,is then intermittently heat sealed in the transverse direction bysealing bar 36 to form an end seam 38 extending across the width offolded tube 12, and securing together therealong its respectiveoverlying twoand fourply portions. A cutting means or knife 40 thenparts the folded and sealed tube 12 in the transverse direction at alocation remote from the end seam 38 to obtain a unit bag element 10.Actually the sealing bar 36 and knife 40 can perform their functionssimultaneously with the sealing bar 36 forming the end seam 38 on anupcoming bag element 10, while knife 40 located adjacent to anddownwardly therefrom separates from the folded tube 12, the previouslyend sealed bag element 10.

Bag element comprises a generally tubular body 42 including therein thefolded edge portions 22 and 24, and can be described as defining betweenits longitudinal fold lines 28 and 30, a front wall or first wall 44 andrear wall or second wall 46 in superposed relationship with the firstwall 44 and joined together therewith along the seam 38. The descriptionof these portions as first and second walls will be seen as more aptlyapplied when bag element 10 is unfolded and shaped to provide a fiatbottom bag. Bag element 10 also includes a closed or secured end 48located adjacent seam 38, and an open end 50 located remote from seam 38opposite closed end 48, and across which the overlying plies comprisingbag element 10 remain unsecured to provide a fill opening 52.

The closed end 48 of bag element 10 can be readily shaped to provide aflat or square bottom bag as illustrated in detail hereinafter. For thepurposes of description it is convenient to identify strategic locationsor points on the bag element 10 to better illustrate the shaping step.Points A and B comprise the terminating locations of the inner edges 32and 34 of the fold edge portions 22 and 24 as they merge with the closedend 48. Point D is located on the first Wall 44 of bag element 10adjacent the fold line 30 as best illustrated in FIGURE 2. Point F islocated directly adjacent point D but is defined as being on the secondwall 46. FIGURE 3 shows the distinction between points D and F with line53 indicating the defining edge of first wall 44 hidden from view byfolded edge portion 24, and on which the point D lies. Specifically, asshown in FIGURE 3, points D and -F extend inwardly from seam 38 adistance X, which distance is approximately equal to the distance Xrepresenting the width of folded edge portion 24. Points C and E differfrom points D and F only in that they are located adjacent the fold line28 of bag elemnt 10.

A method of shaping the closed end 48 of bag assemblage 10 isillustrated in FIGURES 4 and 5. Here the first wall 44 and second wall46 are separately grasped by d hands 54 and 56 at points D and F lyingin adjacent relationship thereon, and sharply pulled apart to theposition illustrated in FIGURE 5. As will be noticed in FIG- URE 4, theseparating of the first wall 44 from second wall 46 in this mannerresults in the unfolding of the folded edge portion 24 at locationsbetween the open end 50 and points D and F, with the points D and Fcomprising two adjacent corners of the flat bottom formed. What ineffect has transpired in the shaping step is the shifting of inner edge34 of the folded edge portion 24 to a position in planar alignment withthe linear path of seal 38 securing closed end 48. This shifting of thelocation of inner edge 34 results in the partial unfolding of the foldededge portion 24 as described above, allowing the bag element 10 to bloomout into a fiat bottom structure. Folded edge portion 22 can besimilarly unfolded to complete the formation of the desired flat bottomin bag element 10.

FIGURE 6 illustrates a flat bottom bag 58 formed from the bag element 10by shaping its closed end 48 as described above. Bag 58 includes atubular body 60 having a fill opening 62 at its end portion 64corresponding to open end 50 of bag element 10, and a flat bottom 66located at its other end 68 or end corresponding to the closed end 48 ofbag element 10.

With fiat bottom 66 so formed, a front wall 70 and rear wall 72 aredistinctly perceptible as defined wall portions of the tubular body andcomprise that portion of first wall 44 and second wall 46 of bag element10 located between its open end 50 and the previously defined cornerpoints C, D, E and F. Joining together the front wall to the rear wall72 are side panels 74 and 76 formerly that part of the folded edgeportions 22 and 24 located between the open end 50 of bag element 10 andthe above enumerated corner points C, D, E and F.

Flat bottom 66 of bag 58 comprises the portions of bag element locatedbetween the closed end 48 and points C, D, E, and F and in part includesrectangular end panels 78 and 80 formerly included as portions of thefirst and second walls 44 and 46. End panels 78 and 80 merge along theirouter edges 96 and 98, defined between points C and D and E and F, withthe front wall 70 and rear wall 72, and are joined together along theircommon inner edges 82 and 84 by seam 38.

Flat bottom 66 additionally includes triangularly shaped members 86 and88 comprising the unfolded parts of the folded edge portions 22 and 24of bag element 10. Triangular members 86 and 88 are of two-plyconstruction as shown in FIGURE 7, and each include an inner ply 94 andan outer ply 96 overlying the inner ply 94 and integrally joinedtogether therewith along their common interiorly extending edges 98 and100, which as shown in FIGURE 6, extend between the four corner pointsof flat bottom 66 and the points A and B located on seam 38. The innerplies 94 and outer plies 96 each include substantially commonly locatedside edges and 92 extending between points C and E and points D and F,respectively, with the outer plies 96 merging therealong with the sidepanels 74 and 76, and with inner plies 94 joined together therealongwith the rectangular panels 78 and 80. The inner plies 94 of triangulermembers 86 and 88 are further joined together with rectangular panels 78and 80 by and along their common portions on seam 38. Actually with seam38 dividing the inner plies 94, they can be aptly considered as eachcomprising two separate triangular portions 102 and 104 abuttinglyengaged and joined together along the path of seam 38.

In FIGURE 8 the bag 58 is shown turned inside out and consequently thetriangular members 86 and 88 are located within the confines of the bag58. In this arrangement the outer plies 96 of triangular members 86 and88 can still correctly be termed the outer plies since even though theyare now located with the confines of bag 58 they still are positionedover the inner plies 94.

Bag 58 as shown in the FIGURE 7 drawing can be formed directly from bagelement 10 by turning the bag element 10 inside out and shaking out theportion of the folded edge portions 22 and 24 located between the openend 50 and points C, D, E and F. When formed in this manner, theterminating or raw edges 106 of bag 58 located adjacent seam 38 arepositioned within the confines of bag 58 as is clearly depicted inFIGURE 9, thereby enhancing the overall appearance of the bag 58 andmaking it suitable for containing expensive articles and the likewherein the appearance of the bag is an important aspect in themerchandising of the article. By again revising or turning inside outthe bag 58 of FIG- URE 8, the bag 58 of FIGURE 6 is obtained.

For the flat bottom of bag 58 to be shaped properly it is important thatthe inner edges 32 and 34 of the folded edge portions 22 and 24 do notextend beyond the longitudinal center line 49 of the bag element 10. Ifthe edge portions are folded to a width extending beyond thelongitudinal center line 49 of the bag 10, the flat bottom 66 of bag 58cannot form or shape properly. Also, to more perfectly form fiat bottom66 of bag 10, further shaping by hand can be employed, as, for example,by further hand shaping the triangular members 86 and 88.

The bags of the present invention can be made from most any flexiblematerial which is of suflicient durability or toughness to withstand theshaping of the closed end 48 of the bag element without tearing orotherwise failing in structure. For example only, and where heat sealingis desired to form seam 38, the bag element 10 can be constructed ofsuch heat sealable thermoplastics as polystyrene, polypropylene,polyethylene, Saran, rubber hydrochloride, and similar plastic film orsheet material fusible by the application of heat. Where sealing by heatis not an important consideration, other materials not having excellentheat scalable qualities as, for example, many of the regeneratedcellulose plastic compositions can be employed to construct bag element10. Sealing in these cases can be accomplished by suitable adhesives,solvents or other sealing substances as wopld be most appropriate forthe material selected for the bag. Also contemplated as suitablematerials for forming bag element 10 are sufliciently durable fabricssuch as natural cloths, like cotton or wool, or synthetic materials as,for example, nylon or rayon. Here seam 38 could be formed, for example,by sewing the material together. Laminated or coated materials, as, forexample, a layer of Saran laminated to or coated on a layer ofpolyethylene, are also suitable for bag element 10 provided thequalities as to flexibility and durability are present. Here, where aheat seal 38 is desired, it should be noted that seam 38 requires boththe inner and outer surfaces of bag element 10 to have heat sealablequalities although the inner and outer surfaces need not be heat fusibleor compatible to each other.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in the art that various changes and modifications can be madetherein without departing from the spirit and scope of the invention.

Accordingly, what is claimed is:

1. A normally flatwise disposed bag element comprising a generallyflattened tubular body having a closed end and an open end, the edgeportions of said tubular body being folded in superposed relationtherewith and extending between said closed end and said open end, saidfolded edge portions being short of the longitudinal center line of saidtubular body, a seam included in said closed end and extendingthereacross securing together therealong the overlying plies comprisingthe folded tubular body.

2. The bag element of claim 1 wherein said tubular body comprises athemoplastic and wherein said seam comprises a heat seal across saidclosed end securing together therealong the overlying plies comprisingthe folded tubular body.

3. The bag element of claim 1 wherein said flexible material comprisesWoven fibers.

4. A normally flatwise disposed bag element which can be shaped to forma flat bottom bag, said bag element formed of flexible material andcomprising a generally flattened longitudinally extending tubular bodydefining an imaginary longitudinal center line, said tubular bodyincluding a longitudinally extending edge por tion on each side of saidlongitudinal center line and first and second ends located opposite eachother and extending generally transversely to said longitudinal centerline, said edge portions being folded along a generally longitudinallyextending line so as to be in superposed relationship with said tubularbody and with each edge portion terminating short of said longitudinalcenter line, a seam located adjacent said first end and extendingtransversely across said folded tubular body, said seam securingtogether therealong the overlying plies comprising said folded tubularbody.

5. The bag element of claim 4 wherein the terminating inner edge of eachfolded edge portion respectively is aligned parallel with saidlongitudinal center line.

6. The bag element of claim 4 wherein said seam is at right engles tosaid longitudinal center line.

7. The bag element of claim 4 wherein said flexible material compriseswoven fibers.

8. The bag element of claim 4 wherein said flexible material comprises athermoplastic.

References Cited UNITED STATES PATENTS 2,121,053 6/1938 Robinson 229.532,819,834 1/1958 Brady 22953 3,136,475 6/1964 Geimer 22957 3,143,2778/1964 La Fleur 229 57 r DAVID M. BOCKENEK, Primary Examiner US. Cl.X.R.

